package com.zh.note.leetcode.dp;

/**
 * 63. 不同路径 II
 * dp[i][j] =  dp[i - 1][j] + dp[i][j - 1]
 */
public class LC_63_uniquePathsWithObstacles {

    public int uniquePathsWithObstacles(int[][] obstacleGrid) {
        int m = obstacleGrid.length;
        int n = obstacleGrid[0].length;
        int[][] dp = new int[m][n];


        for (int i = 0; i < m && obstacleGrid[i][0] == 0; i++) {
            dp[i][0] = 1;
        }
        for (int j = 0; j < n && obstacleGrid[0][j] == 0; j++) {
            dp[0][j] = 1;
        }

        for (int i = 1; i < m; i++) {
            for (int j = 1; j < n; j++) {
                if (obstacleGrid[i][j] == 0) { // 当(i, j)没有障碍的时候，再推导dp[i][j]
                    dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
                }
            }
        }


        return dp[m - 1][n - 1];
    }
}
